<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div{
            overflow: hidden;
            width: 200px;
            height: 100px;
            border: 1px solid black;
            border-right: none;
        }
        div::after{
            content: '';
            display: block;
            width: 100%;
            height: 100%;
            background-color: pink;
            transform: translate(50%);
            transition: all .9s;
        }
        div:hover::after{
            transform: translate(0px);
        }
    </style>
</head>
<body>
    <div></div>
</body>
</html>